Reply To: If my piston looks like this, what went wrong?

[Brad Linkus]

Are you sure this is the right piston for the engine? It looks strange to have detonation on the pin side of the piston as usually it is concentrated on the exhaust side if lean. The squish clearance could have been altered when the piston was changed and the base gaskets were not the same thickness as the original piston was set up for from Barry. The only time I have seen this type of detonation is when the clearance between the piston and the head varies from each side. You should have .030 minimum clearance between the piston and the head all the way around with a minimum cc of 10.5 if the head is not o-ringed.